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Laboratory and Numerical Modeling of Hydraulic Behavior of Saturated Fine Grained Soils Dewatered by Electrokinetic Geosynthetic

Shahsavand, Mohammad | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44851 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali; Shariatmadari, Nader
  7. Abstract:
  8. Most available methods which are well able to improve or dewater coarse soils have little success dealing with fine soils and clays and using these methods to dewater clays needs great amount of time and money. Electrokinetic Geosynthetic is one of new methods that have had a promising future. Regarding the importance and tremendous usage of dewatering in fine soils, the efficiency of electrokinetic geosynthetic method in dewatering fine soils has been taken under the consideration in this research. Following laboratory experimentation, numerical modeling of this process has been done. In this research some laboratory test has been done on kaolinite clay and the effects of pH of specimen, applied voltage and water content on the efficiency of electrokinetic geosynthetic on kaolinite clay has been taken under consideration. During tests flow volume, voltage and pH of different parts of specimen were recorded. Changing pH of pore water from neutral to acidic estate, total flow volume would reduce by 65 percent. This reduction for changing from neutral to alkaline estate is 50 percent. Due to vast reduction of flow volume, the effects of pH on the flow volume are of great importance. So for correct prediction of flow volume it is important to consider electroosmotic coefficient as a variable that changes by changing pH of pore water. By reduction of applied voltage, reduction in flow volume was obvious which indicates that for every pH, there might be a voltage threshold and for values less than that, there would be no electroosmotic flow. Other significant result was increase of aforementioned threshold by changing pH of pore water from neutral to other estates. This threshold would be greater in acidic estate than alkaline estate. By increasing water content, flow volume increased and by reduction in applied voltage this difference would be bigger and bigger and by reduction in water content, voltage threshold was increased. By reduction in applied voltage, proposed model showed better results and by increasing applied voltage, proposed model started to drift apart from recorded results. This could be due to changing the estate of flow from laminar to turbulent. From the experimental results and numerical modeling, some predictive lines were proposed which could predict the total flow volume during the time of test. Using initial pH it is possible to tell how much water could be extracted from the specimen using voltages between 2.5-5 v. generally proposed numerical model could predict the total volume of water extracted during the test with correct trend and acceptable errors
  9. Keywords:
  10. Geosynthetic ; Drainage ; Electrokinetic Process ; Electrokinetic Permeability Coefficient ; Pore Water PH ; PH Changes

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